tree fc630ae7c7e5e0ec67edddbe5231bdacb47ef699
parent 7d88e08078f90c6d182776aa03000494d306b0a7
author Joe Loser <joeloser93@gmail.com> 1634092258 -0400
committer Copybara-Service <copybara-worker@google.com> 1634092532 -0700

[libc++][docs] Mark LWG3274 as complete

Mark LWG3274 as complete. The feature test macro `__cpp_lib_span` was added in
`6d2599e4f776d0cd88438cb82a00c4fc25cc3f67`.

https://wg21.link/p1024 mentions marking `span:::empty()` with
`[[nodiscard]]` which is not done yet. So, do that and add tests.

Reviewed By: ldionne, Quuxplusone, Mordante, #libc

Differential Revision: https://reviews.llvm.org/D111516

GitOrigin-RevId: 8e92410ecc86f3ad29e038bf1abad7aa3fc20e7b